Frequently asked questions about fire ants

Please report suspect fire ants online or contact Biosecurity Queensland on 13 25 23.

Where are they from and how did they get here?

Fire ants are from South America and are native to the floodplains of the Paraguay River in Brazil, Paraguay and Northern Argentina. They entered the southern United States in the 1930s, probably in soil used as ship ballast, and have been spreading across the US ever since.

Fire ants would have been unknowingly imported into Brisbane, possibly up to 20 years ago. The pathway of entry into Brisbane is unknown, but was possibly in a shipping container from the United States. They were first detected in the Brisbane area in February 2001.

Where have fire ants been found in Australia?

In Australia, there have been six separate incursions of fire ants. Five recorded in Queensland; and one in Port Botany NSW.

In Queensland, the first two incursions were discovered in 2001, one in the south western suburbs of Brisbane and the other at the Port of Brisbane. The third and fourth incursions were found in Yarwun, Central Queensland in 2006 and 2013. The fifth and most recent incursion to Queensland was found at Brisbane Airport in 2015.

The Port Botany incursion was discovered in 2014 with the NSW Department of Primary Industries leading the eradication response. Biosecurity Queensland provided assistance in the initial response and provides ongoing scientific and operational support when required.

Both the Port of Brisbane and the 2006 Yarwun incursions have been successfully eradicated and the 2013 Yarwun incursion is due to be declared eradicated in July 2016. Spread from the initial Brisbane infestation has led to infestations around the greater Brisbane area including Ipswich, Logan and Redlands. Isolated infestation has also been found in Scenic Rim, Gold Coast and Lockyer Valley.

View a map of the fire ant biosecurity zones.

How do they spread and how long do colonies take to establish?

Fire ants spread naturally through mating flights and budding:

  • a mated female (queen) can fly up to 2 km        
  • a newly mated queen finds a suitable nesting site, sheds her wings and starts a new colony        

Human-assisted spread:

  • via shipments of infested nursery stock, soil, or other restricted items        
  • potentially many other materials and containers stored in a fire ant infested area        

Fire ant nests can have a single queen or multiple queens. A new queen will lay up to 20 eggs initially. Eggs hatch in 7-10 days and become adults after 9-15 days. A queen can increase egg laying up to 800 eggs per day after initial hatching.

How do I tell fire ants from common or native ants?

Key characteristics:

  • Fire ant workers come in an unusual variety of sizes within one nest        
  • Fire ant workers are small (ranging from 2-6 mm)        
  • Fire ants are copper-brown in colour, with a darker abdomen        
  • Fire ants inflict a fiery sting and are usually aggressive        
  • Fire ant nests usually have no obvious entry hole        
  • The inside of a fire ant nest has a honeycomb structure        
  • A mature nest is often dome-shaped if in an open area but can also be found under logs, rocks or garden materials        

Where should I look for fire ants?

Look around any areas of disturbed ground as well as:

  • in pot plants on the ground        
  • in stores of topsoil, mulch and potting mixes        
  • under landscaping materials (e.g. logs, stones)        
  • under timber or pallets on the ground        
  • adjacent to buildings and other structures        
  • in untidy or overgrown areas        
  • near areas of permanent water (e.g. the banks of dams, rivers, ponds, aquaculture containers)        
  • tufts of grass in open areas, where the soil is built up around the tufts       

What should I do if I get stung and have a reaction?

Stings from fire ants cause a painful, burning and itching sensation that can last for up to one hour. Apply a cold compress (or ice) as soon as possible to the affected areas to reduce swelling and relieve pain. After a few hours (or even a day or two), a small blister can form at the site of each sting. To prevent secondary infection, wash the blisters gently with soap and water and be careful not to break the blisters.

In rare cases, fire ant stings can be lethal to people. If a severe allergic reaction occurs, please seek immediate medical attention.

Why are they a problem?

Fire ants are a serious pest that threatens our lifestyle, environment and agriculture.

What is being used to control fire ants?

Biosecurity Queensland is using a low-toxic bait treatment, which consists of coarsely-ground corn soaked in soybean oil and an insect growth regulator (IGR), either S-methoprene or pyriproxyfen. S-methoprene is widely used in mosquito control programs in the Brisbane region. Pyriproxyfen is commonly used as an IGR in dog/cat flea collars.

The bait is applied by broadcasting it over an area using about a teaspoon per square metre. Worker ants take bait granules back to the nest, where they are passed among other ants and fed to the queen. These baits do not kill the ants but sterilise the queen and stop the larvae from developing. The worker ants are not replaced and the colony dies out.

Why does my property require treatment if I don't have fire ants?

As part of the National Fire Ant Eradication program, Biosecurity Queensland undertakes a baiting program for fire ants on properties in the fire ant treatment area. The bait is distributed within the vicinity of where a colony has been found as a precautionary measure and also so any foraging fire ants can collect the bait and take it back to the nest. Developing nests could be present on your property only becoming visible as they mature.

How is the bait distributed?

There are three main methods of distributing the bait, including:

  • by foot, with a hand held spreader        
  • by all terrain vehicle (ATV) or quad bike        
  • by air, using a helicopter.        

The method of bait distribution varies depending on the size of each property and accessibility. Officers use hand-held spreaders on residential blocks and ATVs are used on properties larger than 5000 m2. Properties larger than 5 ha are targeted for aerial treatment.

How safe is the bait treatment?

The bait treatment has very low toxicity to humans and animals. The bait is scattered thinly and any not taken to the nest following treatment will quickly break down by the next day.

What about biological control methods?

The aim of the current program is eradication. Biological control of any pest will only decrease its numbers, and is therefore not part of an eradication program.

The US is using biological control agents from the fire ant's native habitats. One of these is the parasitic phorid fly. Although this fly controls only about 3% of the fire ant populations in South America, its presence frightens foraging ants and interferes with their ability to gather food. Phorid flies could be a useful addition to chemical control in heavily infested parts of the US, where even small differences are worthwhile.

Fire ant nests in Australia are destroyed when found, so phorid flies could not survive here.

What about boiling water, petrol or kerosene? Surely these would work?

Don't do it!

Boiling water will kill some ants but rarely the whole nest. Remaining ants will just move to a new location. The risk of scalds or burns to people makes attempting this method of control dangerous.

Petrochemicals like petrol, diesel or kerosene are dangerous to handle and will kill any plant material they touch. Some of the residue remains in the soil and may leach or run off into ground and/or surface water to pollute the environment. The risk of injuries from fire and explosions makes attempting this method of control dangerous.

Is the treatment program working?

Yes. The fire ant infestation discovered at Yarwun, Central Queensland in 2006, was eradicated following a successful treatment and pest freedom verification program in 2010. No fire ants from the Port of Brisbane population have been found since 2005, and in 2012 movement controls were lifted from north Brisbane suburbs where a restricted area was in place.

Fire ant eradication is a constant battle, but scientific modelling demonstrates that with committed effort, eradication can be achieved. The eradication program has some new weapons in the war on fire ants with remote sensing, odour detection dogs and micro-satellite genetics all helping find the ants. But the most important factor in the campaign has not changed, and that is members of the public making their contribution by reporting suspect ants and following movement controls.

What is a fire ant biosecurity zone?

A biosecurity zone has been established and movement controls are in place to prevent the spread of fire ants in South East Queensland. The Biosecurity Act 2014 places obligations on people to reduce the risk of spreading fire ants. This includes controls on the movement of items that could carry fire ants.

The biosecurity zone has been divided into three zones which have different levels of movement controls. View a map of the fire ant biosecurity zones.

What are fire ant carriers?

Controls apply to the movement of restricted items within and out of the Fire Ant Restricted Area. Restricted items

Fire ant carriers are materials that could harbour fire ants. They include:

  • soil (includes fill, clay, overburden, scrapings, topsoil, decomposed granite (deco), potting media and any other material from the ground)        
  • mulch        
  • manure        
  • baled hay        
  • pot plants        
  • turf        
  • poultry litter          

What do I need to do if I'm moving soil?

As the movement of soil is the greatest risk of spreading fire ants, there are measures you must take to fulfil your general biosecurity obligation before moving soil. These measures could include one of the following:

  • Checking for ants before moving the soil    
  • Removing the top 1 metre of soil immediately prior to the movement    
  • Disturb the soil through a mechanical process such as grinding, crushing etc    

There are three fire ant biosecurity zones with different levels of movement controls.

Who do the controls apply to?

It is everyone's responsibility to stop the spread of fire ants, which threaten our lifestyle, economy and environment. Controls apply to everyone - residents and commercial organisations.

If you are moving fire ant carriers in the biosecurity zone, you must be aware of your legal obligations. This includes understanding the risks of spreading fire ants and addressing those risks. Refer to movement controls.

Should I care about them if I live in an area that doesn't have them?

Yes. They could spread to your area. The eradication program has a comprehensive plan to find, contain and destroy the ants but fire ants are not an easy pest to get rid of. Your best protection is your own vigilance - look for signs of fire ants in your neighbourhood.

What can I do to help prevent the spread of fire ants?

There are many ways in which we can all help prevent the further spread of fire ants and achieve eradication, by:

  • understanding what fire ants look like and what they might be moved in        
  • being aware if you are living or working in the fire ant biosecurity zone        
  • reporting suspect fire ants to 13 25 23

Last updated 01 July 2016